The present invention relates to noninvasive medical devices and, in particular, it concerns a noninvasive device for measuring the glucose level in the blood.
By way of introduction, Diabetes is one of the most widespread non-infectious diseases in the world. The occurrence of diabetes has rapidly increased over time, and at the current time, the amount of patients having diabetes in the world has reached 100 million people (about 4% of the world's population). One of the problems in diabetes development is the low awareness of the population about the disease. The amount of registered patients having type II diabetes, which is estimated at 85-90% of the diabetic patients, is 3 to 4 times less than the actual population having the disease. Early diagnosis of diabetes is an important factor in controlling this socially significant pathology and in treating the disease.
A basic diagnostic criterion of diabetes is the concentration of glucose in the blood. Measuring glucose concentration in the blood requires, as a rule, laboratory measurements that involve withdrawal of blood for biochemical analysis. There are instruments that directly measure the glucose level in the blood; however, all of them require the withdrawal of blood from the person.
For people with diabetes, a rapid glucose measurement method is desired since these subjects have to inject insulin several times a day according to the glucose measurement. Additionally, in order for those people to run a normal life style, the measurement and the injection have to be rapid procedures. An example of a device for express measurement of glucose level is the glucometer, which is manufactured by “one touch” in the USA. The measurement of glucose concentration in the blood is carried out by an optical method. The range of the measurement is from zero up to 33.3 mmol/l, with an error of ±20%. The duration of the analysis takes about 45 seconds (according to nameplate data).
Other analogues have been developed, such as the device disclosed in U.S. Pat. No. 5,028,787 to Rosenthal, et al. that teaches quantitative analysis for measuring blood glucose by analyzing near-infrared energy following interaction with venous or arterial blood. Another method using an near-infrared energy analyzer is disclosed in U.S. Pat. No. 6,043,492 to Lee, et al. Another example is disclosed in U.S. Pat. No. 6,091,976 to Pfeiffer, et al. that describes a method for monitoring tissue concentration in which a perfusion solution is conveyed as a liquid column through a microdialysis probe implanted in the tissue and is moved to a test cell preferably arranged outside the patient's body. Other methods and devices are disclosed in U.S. Pat. No. 3,958,560 to March.
The aforementioned devices have two major shortcomings. First, the necessity to withdraw blood using an invasive method involves a trauma factor of the risk of contracting an infectious disease. Second, the accuracy of the devices is insufficient, especially in light of the fact that the amount of injected insulin is determined in many cases from the measurements.
Therefore there is a need to have a noninvasive method for measuring glucose level in the blood. As mentioned herein before, in subjects that have diabetes, the measurement is performed several times a day. In addition, there is a huge population that is prone to the disease for different reasons, such as genetic reasons or bad diet habits, that need to be monitored, but abstain from be monitored due to the need to withdraw blood. More recently, several solutions were proposed and disclosed. An example is disclosed in U.S. Pat. No. 6,721,582 to Trepagnier, et al. which teaches a glucose monitoring instrument based on correlating excitation radiation that is radiated and received at the tissue surface. Another example is disclosed in U.S. Patent Application Publication No. 2003/0,144,582 to Cohen, et al, which teaches receiving information from the skin surface in which an optical coupler allows short-term discontinuous and/or continuous information retrieval on dynamic in-vivo glucose levels. Another example is disclosed in U.S. Patent Application Publication No. 2003/0,233,036 to Ansari, et al. where collimated light is passed through a portion of the eye. Another noninvasive method has been proposed to characterize a particular condition and disease by analyzing the exhaled breath of a person or odor from other parts of a body or from an entity. A shortcoming of the aforementioned systems is that they are not sufficiently accurate enough. A further shortcoming of the aforementioned systems is that they are not convenient to use.
There is therefore a need for a noninvasive device and method for determining glucose levels in the blood which is simple to use.